Induction of differentiation of human myeloid leukemias: surface changes probed with monoclonal antibodies

The surface changes occurring in three acute myeloid leukemia cell lines (HL60, ML3, and KG1) induced to differentiate by a variety of agents (dimethylsulfoxide, retinoic acid, 12-O-tetradecanoylphorbol-13-acetate, and factors present in lymphocyte conditioned medium) were probed using monoclonal antibodies that are differentiation stage- and lineage-specific. In all cases, the differentiated phenotype was defective and varied with the inducing agent and the cell line used. HL60 proved to be the most sensitive to the effect of the inducers. Retinoic acid was better than DMSO, and TPA was better than the medium factors in the ability to induce granulocytic and monocytic differentiation, respectively, in HL60 cells. These findings indicate that the differentiation block in acute myeloid leukemias is heterogeneous and that each cell line has different phenotypic characteristics that are responsible for the extent of differentiation obtained with a given inducer. These results also suggest that the extent of the differentiation response in vitro may be improved by the use of more suitable inducers for each specific leukemic line.